The invention relates to a rotary anode x-ray tube comprising an anode which is mounted magnetically without contact, and means for carrying off the anode current.
A rotary anode x-ray tube of this type is described in U.S. Pat. No. 3,878,395. In the case of this rotary anode x-ray tube, the bearing for the rotary anode proceeds by means of a magnetic bearing which provides support axially and radially without contact. The drive motor for the anode comprises a magnetically soft magnetic material which is at the exterior of the rotary anode assembly, and a stator winding at the exterior wall of the tube envelope and surrounding the magnetic material. The magnetic bearing includes an exterior electromagnet whose winding encircles additional magnetically soft material associated with the anode assembly. In the case of this known rotary anode x-ray tube, for the carrying off of the anode current, a mechanical contact is provided between a shaft rotating with the anode and a stationary portion. In the case of this contact, brief interruptions can occur which result in sparking. In addition, metal abrasion occurs.